Pulse generator



all PD 8, 2 1 5, 2

L. P. CROSMAN PULSE GENERATOR June 27, 11950 4 Sheets-Sheet 1 Filed April 5, 1948 June 27, M950 E u.. E. cRosMAN 2,52,851

PuLsE GENERATOR Filed April s, 194s 4 sheets-sheet 2 INVENTOR.

LORING P. CROSMAN BMM ATTORNEY.

June 27, 1950 L, P, CROSMAN 2,512,851

PULSE GENERATOR Filed April 5, V1.948 4 Sheets-Sheet 3 INVENTOR. LQRI NG P. CROSMAN ATTORNEY.

June 27, 1950 l.. P. cRosMAN 2,512,851

n luLsE GENERATOR Filed April 3, 1948 4 Sheets-Sheet 4 ,'Rig. 5.

J f f f 85 87 I f INVENTOR.

LORING P. CROSMAN ATTORNEY.

Patented June 27, 1950 PULSE GENERATOR Loring P. Crosman, Darien, Conn., assigner 'to Remington Rand Inc., New York, N. Y., a-corporation of Delaware Application April 3, 1948, Serial No. 18,782

(Cl. Z50- 27) 4 Claims.

This invention relates to an electric pulse generator and has particular reference to a controlled multivibrator circuit which will deliver a predetermined number of electrical pulses to an output circuit and then turn itself off. While the invention is subject'to a wide range of applications, it is especially suited for use' in an electronic calculator and will be described in that application.

As used 'throughout the specifications and claims, the Lterm unbalanced trigger refers to a trigger stage comprising two electronic triodes with circuit components so adjusted that the circuit is stable only when one triode is conducting and the second triode is non-conducting. Applying an actuating pulse to such a stage momentarily switches conductivity and generates a pulse, the duration of which depends upon the circuit constants. This type of circuit is also called a one-shot multivibrator and a flipnop.

Multivibrator generators have been used in many applications where a square topped electric wave is desirable. In all such applications, including electronic calculating equipment, the multivibrator generates waves continuously as long as the equipment is in operation. Such a system requires accurately timed switching circuits and synchronizingmeans, especially if the operation depends upon the number of pulses used.

It is an object of this invention, therefore, to provide an improved multivibrator circuit which avoids one or morey of the disadvantages and limitations of prior art arrangements.

Another object of the inventionl is to provide a pulse generator which starts generating electrical pulses as soon as desired and stops after a predetermined number of pulses have been gener ated.

Another object of the invention is to provide a multivibrator circuit which may be adapted to provide pulses' for a system of counting using a :radix of live and a radix of two.

Another object ofthe invention is to provide a pulse generator system which will produce a total of five primary pulses but so arranged that selected pulses may be assigned a double value.

The invention comprises a pulse generator for generating a predetermined number of electrical pulses and includes a multivibrator' which is controlled by an electronic switching stage. Two frequency divider stages are included which reduce the number of generated pulses to a single pulse, the output of the second divider stage being coupled back tothe switching stage to cut off the generator at the end of the single pulse.

One featurev of the invention includes an unbalanced trigger stage whch is used to start the multivibrator oscillator. The trigger stage produces a pulse that may be used in conjunction with the multivibrator lpulses for counting and controllingother stages.

For a better understanding of the present invention, togetherk with other and vfurther Objects thereof, reference is made to the followingfdescription taken in connection with the accompanying drawings. a Y. a A

Fig. 1 is a block diagramfshowing how the various stages are connected. a

Fig. 2 yis a schematic'diagram of connections of part 'of the pulse system. a y I Fig. 3 is also a schematic diagram of connections and shows the remaining part of the pulse system. 1 a a Fig. 4 is a diagram which indicates how Figs. 2 and 3 are to be combined toshow the complete system. l

Fig. 5 is a series ovfgraphs showing the character ofthe pulses produced in various parts of the circuit. V. l

Referring now to Fig. 1 the entire system will be generally described, neglecting at present the detailed features of the invention. A starting key I0 is connected'jto a preliminary pulse generator I I which generates a 'sharp pulse when the key contacts are made. Next an unbalanced trigger stage I2 transforms the sharp pulse into a broad flat-topped pulse of 'the same magnitude and duration as the pulses whichlater are generated by the multivibrator. The unbalanced trigger stage I 2 also controls an electronic switching stage I3 which` turns a multivibrator oscillator I4 on. The switching stage I3 is also operated, but in a reverse direction, by a frequency divider stage I6 to turn the multivibrator off.

The output of the multivibrator, in this yexample equal to four pulses, is fed to afrequency divider I5 which reduces the four pulses to two (see Fig. l5-e), and these two pulses are fed toa second frequency divider I6` which reduces the numberof pulses to one (5-f). The output of this divider I6 is fed back over conductors I1 and I 8 tothe switching stage, as explained above,

and the multivibrator is turned off when theland sent to counter stage4 A-I.

,ode 443. .,tube 40 with the controlelectrode circuit of tube conductance in the trigger stage.

iirst pulse, started by the actuation of key Il),y

and transferred by conductor 25, is shown vgraphically by a sharp negative pulse 2B which'o'ccurs at the start of the operation cycle.v The outputof the unbalanced trigger stage I2V is flat-.topped` pulse 21 which is tapped by a buffer cathode follower stage 2I and delivered to a keyboard switchl The output of the control switching stage I3 is shown in Fig. 5c as'a long'` ing assembly 28.

nat-topped wave 3D which must attain its maximum value before the multivibrator I4 can function.

The graph of they multivibrator pulses 3I-d shows thesquare-,topped waves usually produced bysuch a circuit. The waves 32 and 33 (Fig. 5, iand f) produced by the two frequency divider l:circuits are shownin their time relation to the starting pulses, indicating that the. voltage 4fall in the applied wave isthe controlling action Referring again to Fig. 1, the keyboard 28 contains ten manually settable switches which designate and control the number and value of the pulses transmitted to anoutput circuit. If the number to be transmitted iseven, the -pulses Jare delivered to the left-hand side of amplifier vstage 34 (Fig. 3) and transmitted to the even-designated stages in counter-"35 without lcausing any .other pulse. If the number to be transmitted is .which switches conduction in each divider stage.

one, the keyboard switch delivers the pulse to the right-hand side of stage 34 where it is amplified If the number to be transmitted is odd and greater than one,

asingle .pulse is sent to the right-hand side of .fstage 34 while the remaining pulses, representing an even value, are sent through the left-hand side4 `of stage 3.4 to stages 35. -The counter then may be considered to be composed of-two parts, an even-odd stage and a series of five even stages.

plify the circuit,.the. present system is. shown operating a bank of ten lamp indicators 3'I.

Having now described the general system oi pulse generation, reference is made to Figs. 2 and 3 where the detailed schematic Wiringv diagram isv shown. The preliminary pulse generator circuit II-includesa vacuum vtube 4D, a neon gas .tube 4I connected between the anode and control electrode circuit, and a starting key ,IIJ Which-is shunted around va condenser 42 connected between the cathode and control electrode circuits.

The unbalanced trigger circuit .I2-.is adjusted to conduct on the` left side, as indicated in Fig. 2 by cross hatched lines on electronic double tri- Conductor 25 connects the anode of 43 and transmits the preliminary pulse to shift The output pulse generated by the trigger stage .I2 is transmitted over conductor 45 to the; stabilized trigger stage I3containingtube 41, used in this circuit :as a. switch. Anotheroutput circuit is run directamplifier 2l. Conductor 45 is connected to the left-hand control electrode 46 (through a blocking condenser) and can only turn the switch to the on position. Another circuit, to be described later, must be used to turn to the "off position.

, The switching stage I Scontrols the multivibrator I4 by conductor 48 Whichconnects the lefthand anode of tube 4'.' to the right-hand control electrode circuit of the multivibrator tube 5D to control the potential of that electrode. The multivibrator stage I4 is similar to prior art multivibrators which have been described in technical articles and books. In this oscillator only the left-hand anode circuit is tapped to produce positive pulses, the negative pulses being neglected. The multivibrator output is transmitted over conductorsl 5l and 52 to frequency divider I5 and buffer ampliiier 26.

Frequencyv divider I5 comprises a double triode 53 with associated circuits which make it a stabilized trigger. The input conductor 5I to this tube is connected to, both control electrodes through condensers so that each pulse received by the circuit transfersV conductance from the sidethat has been in a conductive state to the other side. To `describe suchl a conductance transfer in this type of circuit the term actuate will be. used hereinafter.` It should be obvious that with anyv even number of pulses applied, such as four, the left-hand anode will pass through the conductive state twice or one half the number of pulses applied. The divided pulses 32 as shown in Fig. 5-e have a Wave form similar to the original pulses, but the time intervals for maximum andvzero voltage duration are twice as long. f

vThe output of frequency` divider stage I5 .is transmitted by conductors 54 and 55 to frequency divider stage I6 and buffer amplifier 22. vThe frequency divider stage IE is exactly the same as stage l5 and divides the two pulses, producing a single pulse (see `curve Fig. 5-f). AThe output of this stage is taken from the left anode circuit of tube 56 and is transmitted by conductors I'I and I8 to the right-hand side of buier stage 2| and the right-hand control electrode of tube 4l. The latter connection is utilized to turn off the multivibrator.

Stage 2 I is a double buffer amplier whose-lefthand elements amplify the single pulse generated by the unbalanced trigger stage I2 and the right-hand elements :amplify the single pulse from stage I6 as described above. Tube 60 in stage 2I is normally conducting and acts as an amplifier in the usual sense. The output circuits from both" halves are taken acrossA cathode resistors 6I and 52 .and transmitted over conductors 63 and 64 to the keyboard 28 where the pulses may or may not be transmitted depending upon the closure of the numbered switches.

From the keyboardtwo conductors and 36 connect to a limiter stage 34. The limiter stage is normally adjusted with its control electrodes below the conducting point so that only positive pulses will cause conduction in the anode circuit. A negative pulse Will have no effect on the tube conductivity. The left-hand side of stage 34 receives a pulse Whenever an even designated key is depressed, the right-hand side is pulsed whenever the one keyv is depressed, and both sides are pulsed Whenever the 3, 5,. 1, or 9 keys are depressed.

The odd or right-hand section of stage 34 has its output connected to trigger stage A-I which is normally conducting on the left-hand side. A pSt-Vel 'pulse' transmitted Ovel* bl'iductl" 56 prilducs a negative pulseiri anode conductor 61 and actua-tes stage` A-f, transferring the conducting path within thev tube tothe' right-hand side. 'Ihis lowers the potential of conductors 68 and 'lil and delivers anegative pulse to the control electrode of'tube' li in an amplier stage T2. Stage 'H' acts as' a buier amplier and inverter, the anode beingv connected directly to conductor T3 which iritur'n is connectedv to all the right-hand control electrodes of a series of five trigger stages. These five stages represent the even numbered digits in thel decimal system and arel designated ifi-0, A4,- A4, A-B, and A- to indicate the values handled by them. The A-U stage has part of its output connected to the left-hand control electrede of the A-2 stage; the output of the A-2 stage is connected to the left-hand control electrode of the A-4 stage; 'the A-4 and A-G stages bei-ng similarly connected, and the A-B stage output' connected back to the control electrode` of the Rems-tage.

Each of the ve stages, A-U to A-8, inclusive, has the output of its left-hand section connected tol one terminal of two neon indicator lamps in they indieator'bank It?. The other terminals ofthe are connected by' conductorsV 14 and 'l5 to rectifying elements 'Itv and "Il and then to the two anodes in stage A-l.

As zeorize or normalizing key 18 is included in series with one of the cathode conductors Bn so that its opening will insert a resistance in series with all the cathodes that normally should be nonconducting.-

In order to describe the operation, let it first be' assumed that the circuit is in its' normal or quiescent state'.- Counter stages A-I A-2, A-4, A-S, and A-B are all conducting on the left-hand Side and A-U is conducting on the right. Neon indicator lampA T9 is burning because one of its conductors 87 leads to the anode in stage A-U which is at' high potential and the. other conductor M leads-r through rectifier 16 to the anode of stage A-l which is at low potential.

Now assume that the number 4 key'i-n the keyboard 28 be depressed, joining conductor 65 with conductor 8l. Then. the start' key l0 is closed and condenser 4:2 is slowly discharged thereby providing voltage for the ionization of neon tube 4t and impressing a voltage rise on condenser 82. This impresses a sharp positive pulse on the control electrode of tube 40. The results of this pulse are transmitted over conductor 25 to the unbalanced trigger stage i2 which produces a atetopped wave (Fig. 5b) which. is transmitted over conductors 39 and 45 to thecontrolelectrode I6v of switching stage i3 and the buier amplifier stage 2|.

The application of a pulse to control electrode 46- ofA tube t1 turns on the multivibrator by increasing the potential on control electrode 83 to avalue that permits oscillation. The' output of the multivibrator is transmitted over conductor 5 t'o thefirst frequency divider stage l5, at which point an output pulse is transmitted over conductors 54 and 55 to the'buerv amplifier in stage 22. The output of this stage consists of a. double pulse shown in Fig. 5-e and is, transmitted by conductor 8! to key contacts Sli under the number 4- key. Then over conductor 65 to the lefthandv side of amplier stage 34 which normally isL biased to the cut-off point. The output of stage 396 is transmitted over conductor 13 as two sharp negative pulses shown in Fig. 5-Ic.v The pulses are sharpened by the capacitor input and are made negative'v by the anode output circuit. The two pulses are applied to the right-hand cor-it'rolelectrode of all the even counter stages, A-li, A-2, A-4, A-, and A-ii. The first negative pulse 85 actuates only the A-t stage since it is the only stage conducting on the right-hand side; The application of the pulse changes the conduction to the leftshand side and in making the transfer' a negative pulse is sent over con doctor 8S to then-1.12V stage and transfers its coni cluetance to the right-hand side.

When the second negative pulse 8l from stage te arrives. at the counter stages 35 the A-U stage is conducting on the left and the A-z is conducting on` the right, hence only the A-2 stage will be' affected. Its conductance will be transferred to the left and in doing so it will cause the actuation of the A-il stage. Hence at the end ofthe double negative pulsev only the A-fl stage is conducting on the right. This condition causes the number s. neon indicator lamp to light since one ofv its conductors Sil leads to the left-hand anode ofstage A143" whichnow is at high potential while the other conductor 'M leads to the left-hand anode of stage Ae'l which is at low potential.

The' above described action is finished a small interval of time before the end of a pulsing cycle since the' second activating pulse 81 occurs at time t7 as shown onv Fig. 5-7c. The multivibrator contiriues-y with its fourthk pulse and is finally turned ofi by the action of the second frequency divider stage f5 which. sends a pulse at time te over conductor' il to theright-han'd control electrode` of tube il in stage I3 which reduces the potential on conductor 48 and stops the multivibrator action.

After the finish of the pulsing cycle the counter stages 35' and the indicator lamps remain in their operated condition so that they may be ready for additional pulses or until the result may' be copied or transferred to anothery part of the calculator system. When it is desir-ed to normalize the system and return the counter stage to zero condition the switch 1.8 is opened. When this is done, a resistance 9| is placed in series with conductor which connects with all the cathodes that are non-conducting when the device reads zero. If the cathode's are in a conducting condition the addedv resistance causes a potential drop in the cathode supply line which reduces the potential differencebetweeny the cathode and the control electrode to a value where the anode current is completely cut off. The same action increases the voltage of the control electrode in the non-conducting half of the stage until it reaches the conducting state.

InV order to illustrate the action of the A-I stage,A let it be assumed that, starting from the quiescent state, thenine key in the keyboard 28 is' depressed. Then, when the start key IllV is closed, the preliminary pulse from stage Il actuates the unbalanced trigger stage I2 and produces the first fiatetopped wave shownA in Fig. -b; The output of trigger stage I2 is transmitted to the' switching stage i3 as before, but another output conductor 39 transmits the' pulse to buffer amplifier stage 2l and thence from cathode resistor Gl over conductor 63 to one of the contacts 93 in the nine key assembly. The pulse: which is transmitted through these contacts starts attimo t1 and stops at time tz (fsee 7 Fig'. 5-b) and is in advance of the multivibrator pulses.

The multivibrator output to the nine key may be traced from the multivibrator stage over conductors i and 52 to the buffer amplifier stage 20, thence over conductor 94 to the bottom contacts 95 of the nine key.

The top contacts 93 of the nine key connect conductor 63 with conductor 661 which connects to the right-hand side of the amplifier tube in stage 34. Contacts 95 connect conductor 94 with conductor 65 which connects to the left-hand side of the same tube. Thus both sides of stage 34 receive pulses, on the right a single pulse 21 (Fig. 5-22) and on the left four pulses 3l (Fig. 5-d). The pulses are applied to the control electrode through small condensers, hence the anode currents have wave forms as indicated in Fig. 5-m and 5-1. The pulse applied by conductor 66 is amplied and transmitted over conductor 61 to the A-i stage which is thereby actuated and made to conduct on the right.

The four negative pulses transmitted from stage 34 over conductor 13 are all applied to the right-hand control electrodes of all live tubes in n the counter stage 35. The iirst stage A-D is the only stage affected by the first pulse since it is the only stage in this group conducting on the right. When actuated, it transfers its conductance to the left, and in doing so sends a pulse to the next stage A-2 which actuates. it and changes its conductance to the right. When the second of the train of four pulses arrives only the'second stage is affected because now it is the only stage conducting on the right. It changes to the left and as before actuates the next higher stage. This process continues until the last pulse actuates stage .fl-6, transfers its conductance to the left, and actuates the A8 stage by transmitting a pulse over conductor 98. Therefore, at the end of the pulsing cycle stages A-l and A-S are conducting on the right. Under these conditions, number nine neon lamp will be lighted because its upper conductor 91 leads to the high potential point in stage A- and its lower conductor 'l5 leads, through rectiiier '11, over conductor 68 to the low potential point in stage A-l.

Having now described the generation and recording of values of four and nine it will be obvious how the other values are recorded. All even valued numbers are recorded by transmitting a number of pulses to the even numbered ring; the number of pulses being equal to half the number to be recorded. All odd numbers are recorded by actuation of the A-l stage and the recording of the even number one less than the desired odd number.

Actuating pulses for recording two and four are illustrated in Figs. 5-Z and 5-7c by single and double negative pulses and are obtained from frequency divider stages I6 and I5. Actuating pulses for recording eight are shown in Fig. 5-z` and are obtained directly from the multivibrator output. Actuating pulses for recording six are shown in Fig. 5-7' and are obtained from mixer stage 23 by the addition of a single and a double pulse. An inverter stage 24 (Fig. 5-h) and a butler amplifier are employed to obtain the proper segregation and polarity.

From the above description it will be evident that the invention may be employed to furnish electric pulses to electronic calculator systems for recording and adding predetermined values.

While there have been described and illustrated, specic embodiments of the invention, it will be obvious that various changes and modications may be made therein without departing from the iield of the invention which should.

be limited only by the scope of the appended claims.

What is claimed is:

1. A pulse generator for generating a pluralt of electrical pulse trains, each having a predetermined number of electrical pulses comprising, a multivibrator for producing electrical oscillations, an electronic switching stage under control of a manually operated switch for start ing the multivibrator, a plurality of frequency divider stages coupled to the multivibrator for producing said plurality of pulse trains which-include a single pulse, and coupling means be-` tween said frequency divider stages and the elec.- tronic switching stage for turning off the multivibrator when the single pulse ends.

2. A pulse generator for generating a plurality of electrical pulse trains, each having a predetermined number of electrical pulses comprising, a multivibrator for producing electrical oscillations, an electronic switching stage for starting the multivibrator, an unbalanced trigger stage coupled to the switching stage for generating a single pulse when actuated, a manually operated' switch for causing the actuation of said trigger stage, a plurality of frequency divider stages coupled to the multivibrator for producing said plurality of pulse trains which include a single pulse, and coupling means between said frequency divider stages and the electronic switching stage for turning off the multivibrator when the single pulse ends.

3. A pulse generator for generating a plurality of electrical pulse trains, each having a predetermined number of electrical pulses comprising, a multivibrator for producing electrical oscillations, anelectronic switching stage for starting and stopping the multivibrator, an unbalanced trigger stage coupled to the switching stage for generating a single pulse in advance of the multivibr'ator oscillations and for controlling the switching stage to start the multivibrator when the single pulse from the trigger stage ends, a manually operated switchvfor causing the actuation of said trigger stage, a plurality of frequency divider stages coupled to the multivibrator for producing said plurality of pulse trains Which include a single pulse from one of the frequency dividers, and coupling means between said frequency divider stages and the electronic switching stage for turning oi the multivibrator when' the single pulse from one of the frequency dividers ends.

4. A pulse generator for generating a plurality of electrical pulse trains, each having a predetermined number of electrical pulses comprising, a multivibrator for producing electrical oscillations, an electronic switching stage for starting and stopping the multivibrator, an unbalanced trigger stage coupled to the switching stage for generating a single pulse in advance of the multivibrator oscillations and for controlling the switching stage to start the multivibrator when the single pulse from the trigger stage ends, means for actuating said trigger stage, a plurality of frequency divider stages coupled to the multivibrator for producing said plurality of pulse trains which include a single pulse from one of said divider stages, coupling means between the divider stages and the switching stage for turning off the multivibrator when the single pulse 9 from one of the divider stages ends, and connecting means from two or more frequency divider stages through a mixer stage to a. utiliza.- t-ion circuit to obtain a number of pulses not an integral sub-multiple of the number deliv- 5 ered by the multivibrator.

LORING P. CROSMAN.

REFERENCES CITED The following references are of record in the 10 le of this patent:

Number 10 UNITED STATES PATENTS Name Date Reeves Feb. 3, 1942 Dickinson July 2, 1946 Mumma. Aug. 13, .1946 Miller June 24, 1947 Anderson et al. Nov. 11, 1947 Grosdoi Mar. 2, 1948 Moore June 22, 1948 Crost June 29, 1948 

